Backpack



FIG. 1 shows a top and side perspective view of a backpack.

FIG. 2 shows a front view thereof.

FIG. 3 shows a first side view thereof.

FIG. 4 shows a second side view thereof.

FIG. 5 shows a top plan view thereof; and,

FIG. 6 shows a bottom plan view thereof.

The smaller-length dotted lines reflect stitching and are part of the claimed design. The longer-length dotted lines show portions of the backpack and form no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 